Method for automatically regulating and controlling thickness of deposited film in LPCVD (low pressure chemical vapor deposition) furnace tube

Abstract

A method for automatically regulating and controlling the thickness of a deposited film through an LPCVD furnace tube comprises the steps that the LPCVD furnace tube is provided, thermocouples and monitoring pieces are arranged, and a placement area is divided into control areas through the monitoring pieces; filling unpatterned wafers in the control areas, and performing corresponding process test operation; measuring the deposition film thickness of each monitoring sheet, and feeding back the deposition film thickness to the regulation and control system; the regulation and control system regulates operation time and temperature according to the difference between the measured thickness and the target thickness, and the operation time and temperature serve as reference time and temperature; during goods running, the Lot number, the Lot position, the wafer number and the patterning density are sent to a regulation and control system, the average patterning density of all areas is obtained through calculation, and then the thickness, needing to be compensated, of all monitoring pieces is obtained through calculation; the regulation and control system calculates the time and temperature needing to be compensated according to the compensation thickness, and further calculates the deposition time and temperature of the current batch on the basis of the reference time and temperature; and the regulation and control system assigns the regulated deposition time and temperature to the corresponding PPID of the machine table to execute operation. According to the invention, the thickness of the deposited film can be automatically regulated and controlled by the LPCVD furnace tube.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method for automatically regulating the deposition film thickness of an LPCVD furnace tube. Background technique [0002] As we all know, for low pressure chemical deposition (Low Pressure CVD, LPCVD), in addition to being affected by the temperature of the furnace tube, gas flow, and pressure, the thickness of the deposited film on the wafer surface is also affected by the patterning density of the crystal plane. The more densely patterned a wafer is, the more surface area it has, and the more gas it consumes to deposit the film. [0003] For the LPCVD vertical furnace tube, a certain number of wafers are placed on a bracket with a fixed distance (boat) from top to bottom and enter the reaction chamber (Tube) to perform the deposition reaction. During the deposition reaction, the reaction gas flows from bottom to top in the reaction chamber. Placing produ...

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Problems solved by technology

Placing products with high patterning density at the lower end will consume more reaction gas, resulting in the reduction of reaction gas flowing to the upper end, and the film thickness deposited on the wafer at the upper end is thinner; on the contrary, placing products with low patterning density at the lower end will cause Thick film deposited on wafer

[0004] Obviously, due to the diversity of products and processes in the FAB, the patterning density is also very different. Each operation batch contains products with different patterning densities, which will inevitably cause great differences in the film thickness of the product deposition. And then affect the stability of product yield

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